The present invention relates to the fields of purchase authorization and radio frequency communication and, more particularly, to antenna assemblies, methods and service stations useful, for example, for fuel-purchase authorization.
In the past a gas station was primarily a location to purchase fuel for a vehicle and occasionally to purchase comestibles and products associated with vehicular operation. Increasingly, gas stations are transforming into service stations, becoming one of the most important retail venues in industrialized society. The reasons for the increasing importance of service stations as retail venues, as well as the nature of the purchases, result from the relative advantages of service stations which are dictated by the primary purpose of service stations: efficiently providing fuel to vehicles.
To be successful as a gas station, a service station must generally be located on a heavily traveled road with large area available for both high speed entrance and egress, many fuel-dispensing locations (i.e., fuel pumps), arranged for high-throughput refueling of many continuously arriving vehicles.
One preferred method for increasing the attractiveness of a service station is through the use of automated payment for fuel. In such methods, a vehicle is equipped with a vehicle identification tag storing data relating to the vehicle identity and a payment method. Each fuel-dispensing location is provided with a vehicle identification tag-reader including using a tag reading transceiver provided with a vehicle identification tag reader antenna that is configured to wirelessly read the vehicle identification tag.
In order to reduce fuel theft and in order to reduce interference between identification tag readers, it is accepted to limit the range of the wireless communication (as measured between the vehicle identification tag and the vehicle identification tag reader antenna), typically to only a few centimeters. Thus, vehicle identification tags are generally located in proximity of a vehicle refueling port and vehicle identification tag reader antennae are generally secured to a fuel-dispensing nozzle associated with a specific fuel-dispensing location so that the tag reader is able to read the identification tag substantially only when the fuel-dispensing nozzle engages the vehicle refueling port.
Generally, associated with the vehicle identification tag reader is a tag reader station communication transmitter, configured to forward information read from a vehicle identification tag to a service station controller. A tag-reader station communication transmitter is generally in wired communication with the tag reading transceiver itself and is physically attached to the fuel-dispensing nozzle or to the fuel dispensing location with which the fuel-dispensing nozzle is associated. The tag-reader transmitter is generally in wired communication with a service station controller, for example through the underground wired communication channels that exist in any case between the service station controller and the different fuel-dispensing locations.
When it is desired to purchase fuel, a fuel dispensing nozzle of a fuel dispensing location is placed inside the refueling port of a vehicle, bringing the tag reading antenna of the tag reader in wireless communication range with the vehicle identification tag. Information (such as vehicle identity) read through the tag reading antenna is forwarded to the service station controller by the tag reader station communication transceiver along with the identity of the fuel-dispensing nozzle with which the respective tag reader is associated. Based on the applicable rules, the service station controller optionally communicates an authorization signal including if, under what conditions and how much fuel to dispense to the identified vehicle through the fuel-dispensing nozzle.
In a large part due to the use of wired communication between the various subsystems especially between the identification tag reading antenna and the tag reading transceiver, and between the tag reader station communication transmitter and the service station controller, installation, maintenance and upgrading of an automated fuel payment system is difficult. Once a fuel station has invested in a given system, it is often prohibitively expensive to replace the system, causing service stations to use obsolete automated fuel payment systems.
In the art, a number of systems and methods for automated fuel payment have been proposed that overcome some of the disadvantages of wired systems such as the discussed above.
In the PCT patent applications published as WO 2007/049273 and WO 2007/049274 of the Applicant are taught wireless vehicle identification tag readers as well as systems and methods using the wireless vehicle identification tag readers. Each wireless tag reader is configured to be secured to a fuel dispensing nozzle and includes a wireless tag reading transceiver functionally associated with an identification tag reading antenna, a wireless station communication transceiver and an autonomous power source. In FIG. 1, a nozzle-mounted wireless vehicle identification tag reader 10 is depicted secured to a fuel dispensing nozzle 12.
When it is desired to purchase fuel using such wireless systems, a fuel dispensing nozzle (such as 12 in FIG. 1) of a fuel dispensing location is placed inside the refueling port of a vehicle, bringing the tag reading antenna of the vehicle identification tag reader (such as contained within the casing of tag reader 10) in wireless communication range with the vehicle identification tag. Information (such as vehicle identity) read by the tag-reading transceiver of the tag reader through the tag reading antenna is forwarded to the service station controller by a wireless station communication transceiver (such as contained within the casing of tag reader 10) along with the identity of the fuel-dispensing nozzle with which the tag reader (e.g., tag reader 10) is associated. Based on the applicable rules, the service station controller optionally communicates an authorization signal including if, under what conditions and how much fuel to dispense to the identified vehicle to the fuel dispensing controller which forwards the authorization signal to the appropriate fuel dispensing location through the existing wired communication.
Installation and removal of a nozzle-mounted wireless vehicle identification tag reader such as 10 is easy, allowing simple and cheap hardware upgrading. Maintenance is not difficult, but due to the simplicity of the wireless tag readers and the ease with which the wireless tag readers may be attached and reattached to a fuel dispensing nozzle, it is often simpler and cheaper (and thus preferred) to discard a malfunctioning or spent wireless tag reader.
In the above referenced PCT patent applications are also taught vehicle-mounted wireless active identification tags including a radio-frequency transmitter used in some embodiments to communicate with a service station controller. Such vehicle-mounted wireless active identification tags are preferably self-contained and are provided with an autonomous power source to prevent tampering or abuse.
A problem with the teachings of the above-referenced PCT patent applications is that the wireless communication systems described to date are not sufficiently robust, so that under certain conditions a service station controller fails to establish or maintain wireless communication with a transmitter of a nozzle-mounted vehicle identification tag reader or of a vehicle-mounted active identification tag. As is clear to one skilled in the art, the robustness of communication during any type of commercial transaction, especially high throughput commercial transactions such as common in service stations, is critical.
The Inventor has identified that one of the challenges encountered when implementing wireless communication between a service station controller and a nozzle-mounted vehicle identification tag reader or a vehicle-mounted active identification tag is related to antenna polarization.
As is known to one skilled in the art, due to the limited number of available radio-frequencies there is a strict allocation of radio-frequencies for any given application. The most readily available frequencies for use for automated fuel payment system are very high frequencies (VHF, 30 MHz to 300 MHz) and ultra high frequencies (UHF, 300 MHz to 3 GHz). Such frequencies are very susceptible to coupling loss resulting from mismatch between the polarization of a transmission antenna and a reception antenna, e.g., between the transmission antenna of a nozzle-mounted vehicle identification tag reader or of a vehicle-mounted active identification tag and the reception antenna of the receiver of the service station controller.
It is known in the art when using wireless VHF or UHF communication to orient the reception and transmission antennae relatively close to vertical (the Y axis, where the X-Z plane is defined to be substantially parallel with the ground), for example, as is known from vehicle-mounted or portable radio frequency receivers and transmitters.
In an automated fuel payment system it is not practical to ensure sufficiently similar orientation of the reception antenna of a receiver of a service station controller and the transmission antenna of a nozzle-mounted transmission antenna of a vehicle identification tag reader transmitter. A fuel dispensing nozzle in place in a refueling port of a vehicle may be in virtually any orientation and depends on many factors including the distance from the fuel dispensing location which the vehicle is parked, the angle at which the vehicle is parked, the type of vehicle (motorcycle, scooter, automobile, SUV, light truck) as well as the make and model of the vehicle.
In an automated fuel payment system it is not practical to ensure sufficiently similar orientation of the reception antenna of a receiver of a service station controller and the transmission antenna of a vehicle-mounted active identification tag. The fact that the wireless transmitters is vehicle-mounted means that the exact orientation of the transmission antenna relative to the receiver antenna of the service station depends on where the vehicle has stopped in the service station, the type, make and model of the vehicle.
In the art it is also known to provide wireless VHF and UHF communication systems with excess transmission power so even if there is a large polarization mismatch between the transmission antenna and the reception antenna, sufficient signal is received, albeit with greater than usual noise. It is impractical to provide a small, portable and cheap transmitter such as a vehicle identification tag reader transmitter with excess transmission power. First, as the tag reader transmitter is mounted on a fuel dispensing nozzle, the transmitter is in close proximity to explosive gasoline fumes. The higher the power of such a transmitter the more likely it is that the transmitter produces sparks or generates excess heat, potentially leading to a catastrophic situation. Further, in the above-referenced PCT patent applications are disclosed embodiments of self-contained vehicle-identification tag readers with integral power supplies. It is preferred that such tag readers use as little energy as possible to allow reduction of the size and the capacity of the integral power supply to allow reduction of price of the tag reader and to reduce maintenance costs related to recharging and replacing the power supplies of such tag readers. It is also clear that it is impractical to provide a self-contained vehicle-mounted active identification tag including an autonomous power source with excess transmission power.
In the art it is also known to provide wireless VHF and UHF communication systems with antennas having an adjustable orientation. When polarization mismatch is identified between a transmission antenna and a reception antenna, one or both antennae are moved to reduce polarization mismatch until a reasonable signal is received. Automatically adjustable antenna are complex, expensive, difficult to implement and susceptible to malfunction. Further, as the reception antenna associated with the receiver of a service station controller must typically communicate with a plurality of differently oriented nozzle-mounted vehicle identification tag readers and a plurality of differently oriented vehicle-mounted active identification tags, it is impractical to use an adjustable reception antenna. Further, as noted above it is desirable that a nozzle-mounted vehicle identification tag reader or vehicle-mounted active identification tag be cheap, simple, energy efficient, small and reliable, all properties that render the use of an adjustable transmission antenna impractical.
In the art it is also known to provide wireless VHF and UHF wireless communication systems with circularly polarized antennae. Circularly polarized antennae are generally more expensive, complex and bulky than other antenna types.
In the art it is also known to provide wireless VHF and UHF wireless communication systems with low-gain antennae. Low gain VHF and UHF transmission antennae are inefficient, wasteful of power, have a relatively short range and have relatively high noise.
In the PCT patent applications published WO 2007/049273 is taught the use of wireless relays between vehicle identification tag reader transmitters and a service station controller receiver as additional components of an automated fuel payment system. By shortening communication ranges and by increasing the number of communication paths available between a given vehicle-identification tag reader and a service station controller, a more robust system is achieved. This is not an ideal solution due to the added expense of manufacture, installation and maintenance of wireless relays.
It would be highly advantageous to have a communication system for a service station allowing robust wireless communication between a service station controller and one or more moveable transmitters such as vehicle-mounted or fuel-dispensing nozzle mounted transmitters. It would be highly advantageous that the wireless communication be simple and cheap to maintain and produce.